In the matter of the termination of a works contract for breach by the employer, where restitution in kind to the contractor of the partially completed works is not feasible, the content of the restitutory obligation incumbent upon the employer must be determined by reference to the amount of the consideration originally agreed, inclusive of the sum due by way of price revision if separately provided for, and not by reference to the market value of the works at the time of the ruling on termination. It follows that the arbitral award which assessed the consideration for the works carried out at current market prices rather than at the prices stipulated in the contract is vitiated by nullity.